Method for the recovery of phosphorus fumes evolved in the volatilization method of treating phosphate-rock.



UNITED STATES Idfiaiil iifili' GB ALBERT R. MERZ, WILLIAM H. ROSS, AND JQHN Ii. CAEOTHERS, 3F HASHINGTQN, DISTRICT OE COLUMBIA,

METHOD FOR THE RECOVERY OFPI-IOSPHORUS FUMES TION METHOD OF TREAT. ENG PHDS Specification of Letters Patent.

No Drawing.

(DEDICATED T0 (whose post-ofiice address is Department of Agriculture, \Vashington, D. (1,) have invented a new and useful Method for the Recovery of Phosphorus Fumes Evolved in the Volatilization Methodof Treating Phosphate-Rock.

This application is made under the act of March 3, 1883, chapter 143 Stat, (525), and the invention herein described and claimed may be used by the Government of the United States or any of its 0thcers or employes in the prosecution of work for the Government, 'or any person in the United States, without payment to us of any royalty thereon.

In the volatilization method of treating phosphate rock the latter is mixed with col-re and silica in the proper proportions and ignited in an electric or other furnace to such a temperature that replacement of the acid radical of the phosphate rock is effected by the silica added and the phosphorus is evolved in the elemental form. Means are provided for its immediate oxidation to phosphorus pentoxid which in turn is absorbed by a series of absorbing towers. By circulating the acid solution through the towers, a solution may finally be obtained in thislwaycontaining a maximum of phosphoricacid.

7 It is not practical, however, to obtain by this process a stronger solution than 50%,

consequently in the use of such a solution for the preparation of such fertilizing materials as ammonium phosphate anddouble superphosphate the resulting product has to be dried in order to remove the water origi- 45 nally present in the phosphoricacid solution.

A further disadvantage in this method of collecting the phosphorus pentoxid lies in,

the fact that complete absorption of the fumes is dificult to accomplish, requiring a more or less complicated system of absorb- I ,i'ngto'wers. I p v Our invention relates to a process of col-.

Application filed July 3.91s. Serial No.

Patented l's'oerl it THE FUBLIC.)

l current. of gases is then made to pass by suction or otherwise. through a porous filter consisting of any oi. the following compositions: liltrosc, al unduin, lciesclguhr, unglazed porcelain-or earthenware, or of any other similar nature. The filter may be constructed in the form of a series of cylinders or in any other way considered most practical for the recovery of the phosphorus in the form. hereinafter described. in which it is collected.

With iilte of proper porosity has been found p able to make complete recovery of the pl When s am allowed to .miS: with he oxidized Pl'iOE-illllOlllS fumes the filter has the. eti'cct bringing the reacting gases into very intimate contact whereby complete conversiog ut' the phosphorus pentoxid into phosphoric acid is simply effected in the walls of the filter without any circulation of the solution being necessary, and the strength of acid obtained can be regulated compound is suspended through the filter as 0 already described.

Or, finally, if a potassium salt as potassium chlorid is blown in the term at a pow (her into the oxidizing chamber or in the reaction takes chamber succeeding this, I place between the potassium chlorid and the phosphorus pentoxid to form potassium meta-phosphate with evolution of chlorin. By the process of passing the gases containphorus pentoxid in the dry state.

The essence of the invention is the oh I viation of the necessity in. the manufaclnjlre of concel'ltrated phosphorus cnznpeumls of dealing with thc cmnpamtively Weak phosphoric acid snlutlnn obtained in the usual. method in the absorbing; towers" To this end the; phnsphorus cm gouncl is (fntained allre-crly from the inn by the ad: inure of the (leaned sulm use: l steamy ammonia, potassium. in filtering (ml; the w by SHClZlGH m: nth-J suitable fill. txncle name hair: 1: mineral spm'ige. t tent to Sp. 9%,Q82 035' 1911, a sxmilzir material is to separate zinc or lead oxirls frornfuinace gases. We do not claim originality inlhe use of the filter.

What we claim is: A process for recovering phosphorus evolved from phosphate rock by the volatiliza'tion method, consisting in introducing into the fumes of the phosphorus oxils any desired substance which will react, with said fumes and collecting tho resulting compound on a filter. I In testimony whereof, we affix our signatures in the presence of two subscribing witnesses:

ALBQET 7". MEET "1 WILLLXA ll. BO S. JOHN I l. (hlROlHEHS. 

